On Wed, 30 Nov 1994, Toby Bradshaw wrote:
> In article <mwspitze-291194154653 at phar2.medsurge.hsis.uci.edu>,
> matt spitzer <mwspitze at uci.edu> wrote:
>> [snip]
>> >If
> >cognitive functions are modular, then each subsystem, and consequently each
> >function, may be subject to independent genetic control. If so, studying
> >the heritability of IQ (a unitary measure of cognitive ability) makes no
> >sense.
>> By this line of reasoning, it would make no sense to measure the
> heritability of grain yield in maize or stem volume growth in trees,
> since these are the cumulative result of "subsystem" activity --
> nutrient acquisition, photosynthetic efficiency, carbon partitioning
> among organs, resistance to pests and disease, etc. It remains the
> case that "yield" parameters have their heritabilities measured
> all the time as a guide for plant breeding. The complexity of the
> whole system is really irrelevant for calculation of heritability.
> All that matters is that there is genetic variation for at least
> one component of the system. The more components that have genetic
> variation, the more complex the analysis becomes (potentially).
>> -Toby Bradshaw
>toby at u.washington.edu>>>Well noted, but I think what we seem to be missing here is whether IQ is
appropriate to the field of intelligence at all. I replied to the
original poster personally along these lines. First we have to ask
whether intelligence is something which can be measured, then we have to
ask whether IQ can measure it. If intelligence can be defined by IQ then
we're in danger of becoming circular. Remember, the IQ test started off
as a means of identifying children with learning difficulties, and a lot
of other things can contribute to learning difficulties than a "basal
intelligence level". Stephen J. Gould says it a lot better in "The
Mismeasure of Man". Much evil has been done in the name of
the heritability of IQ (recent policy initiatives from the Singaporean
government, come to mind) and the final question we have to ask ourselves
is does it all really matter ?
Peter